Typically, physical and chemical stabilities of substances and formulations are determined in such a way that the substances and formulations are stored in controlled storage conditions for a long period of time. At the beginning of the storage period and time intervals (several weeks, months, years) during the storage, samples are taken from the stored substances and formulations, which are subsequently assayed in a laboratory using physical and chemical analyses (chromatographic, electrophoretic, wet-chemical, and physical methods). These methods have various disadvantages:                The performance of the classical physical and chemical analyses typically requires a large outlay in time since, for example, complex sample preparations are necessary for chromatographic and electrophoretic analyses.        To perform chromatographic analyses, it is typically necessary for reference material having a known content of the substances to be assayed to be present.        The material taken from the stored substances and formulations for the analyses may no longer be used for further storage, since the samples are destroyed in most cases in the classical physical and chemical analyses.        Because of the great complexity, the analyses may only be performed at long time intervals. In comparison to the present invention, it takes significantly longer to obtain conclusions about the stability of the stored substances and formulations from the experimental data.        
For example, a device for determining types of adsorbates, in which an infrared spectrometer disperses a beam of radiation from a catalyst which a gas is subjected to for analysis in order to adsorb adsorbates thereon, is known from DE-A-197 44061. The spectrometer outputs spectral data, corresponding to a wave number of the beam of the radiation, to a computer which has reference data stored. The computer standardizes the spectral data and the reference data and then calculates a product of the standardized spectral data and the reference data. A function of the product in relation to the wave number is then differentiated in order to obtain a differential function. Then, a specific wave number is determined for which the differential function is equal to zero, so that the shared peak of the spectral data and the reference data at the specified wave number is determined precisely.
It is therefore an object of the present invention to provide a device and a method which confirm information about the physical and chemical stability of substances and formulations rapidly, without destruction to the substances and formulations.